| 摘要 |
1,102,144. Electric motors; control of A.C. motors. K. DIEHL. 27 May, 1965 [5 June, 1964], No. 22543/65. Headings H2A and H2J. [Also in Division G3] An electric clock utilizes a synchronous motor comprising a permanent magnet rotor and one stator coil supplied with a synchronizing frequency and a further stator coil connected periodically to a direct current supply by means of switching device controlled by the signal induced in a third stator coil, pulses being fed alternately to the first two coils. As described, the motor may be driven by a dry battery and may be synchronized by a transistorized oscillator of the torsion, leaf-spring, piezo-electric or balance wheel types. In the latter case, the balance wheel (Fig. 1, not shown) carries two pellet-shaped permanent magnets (25) which are arranged to pass a pair of coils 29, 30 during each oscillation. Voltages induced in coil 29 are amplified by transistor T2 and provide current in winding 30 so as to maintain oscillation and provide further current in winding 8 on the stator of the motor to control the speed of rotation. A voltage is induced in winding 10 on the stator of the motor each time a pole of the four-pole rotor reaches a given position. This voltage is amplified by transistor T1, providing sufficient energy in stator winding 9 to maintain rotation at a speed determined by the pulses fed to winding 8. The speed of the motor may be adjustable by replacing the balance wheel oscillator T2 by a source of adjustable frequency signal. Diodes D1, D2 maintain the current in coils 8, 9 independent of supply voltage. Motor construction.-Core-less stator coils 8, 9, 10 may be wound concentrically and cemented to a printed circuit board (Fig. 2, not shown). Figs. 4 ... 7 (not shown) relate to other coreless stator constructions.
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